1. Field of the Invention
The present invention relates to a transmission system suitably applicable to the transmission between an imaging apparatus and an apparatus for receiving or relaying video signals from the imaging apparatus, an imaging apparatus applied to this transmission system, and a transmission method applied to this transmission system.
2. Description of the Related Art
With related-art systems having two or more imaging apparatuses for use in the recording in broadcasting stations, various types of studios, and stages, for example, it is a general practice to generate a reference signal for determining a reference imaging timing and supply the generated reference signal to all of two or more imaging apparatuses. This reference signal includes the vertical synchronous and horizontal synchronous signals of a video signal. Each of the imaging apparatuses outputs a video signal obtained by the imaging that is synchronized with the supplied reference signal. This arrangement provides a video signal having a timing with all video signals supplied from two or more imaging apparatuses synchronized, thereby allowing the smooth switching and editing of images, for example.
Further, in taking images by use of two or more imaging apparatuses, it is sometimes practiced that a control apparatus for controlling each of the imaging apparatuses sends commands to the imaging apparatus to execute various adjustments on the imaging apparatus.
Referring to FIG. 7, there is shown an example of the connection between a related-art camera apparatus and a related-art control apparatus. In this example, a camera apparatus 10 is configured as a relatively small-size, monitorless camera called a POV (Point Of View) camera. The POV camera is often arranged at positions taking advantage of the small size, on drive mechanisms such as small-size cranes and pan tilter and at locations hidden in stages and studios, for example. The camera apparatus 10 is connected to a control apparatus 30 via an adaptor apparatus 20. The adaptor apparatus 20 provides the connection between the camera apparatus 10 and a monitor 21 and a headset microphone 22 and executes relay processing between the camera apparatus 10 that is a POV camera and the control apparatus 30.
In the example shown in FIG. 7, the camera apparatus 10 and the adaptor apparatus 20 are interconnected with three cables of a digital transmission path 1, an analog transmission path 2, and a control command transmission path 3. The adaptor apparatus 20 and the control apparatus 30 are interconnected with an optical fiber cable 4. The distance between the camera apparatus 10 and the adaptor apparatus 20 is often comparatively short, about several meters for example. The distance between the adaptor apparatus 20 and the control apparatus 30 is sometimes very long depending on the system configuration.
The digital transmission path 1 connecting between the camera apparatus 10 and the adaptor apparatus 20 transmits digital video signals imaged and outputted by the camera apparatus 10. The analog transmission path 2 transmits, to the camera apparatus 10 as an analog reference signal, the reference signal transmitted from the control apparatus 30 to the adaptor apparatus 20. The control command transmission path 3 transmits control command between the camera apparatus 10 and the adaptor apparatus 20.
The optical fiber cable 4 connecting between the adaptor apparatus 20 and the control apparatus 30 transmits digital video signals from the camera apparatus 10 to the control apparatus 30 and a reference signal from the control apparatus 30 to the adaptor apparatus 20 as a digital signal. Further, control commands are transmitted as superposed with a digital video signal or a reference signal.
The connection configuration shown in FIG. 7 allows a POV camera not originally having a monitor to be connected with the monitor 21 and headset microphone 22 through the adaptor apparatus 20, thereby achieving substantially the same feel of the operation and use provided by ordinary video cameras.